DBI and Constant

skeight has asked for the wisdom of the Perl Monks concerning the following question:

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Re: DBI and Constant by MeowChow (Vicar) on Feb 12, 2001 at 15:56 UTC
You probably don't need a constant constant for this; just use a variable. This will simplify your connection string, since you can then use Perl's built-in variable interpolation instead of the clunkier concatenation with a constant value: `our $DBNAME = 'database_test'; my $dbh = DBI->connect("DBI:mysql:database=$DBNAME", 'username', 'pass +word') or die;` [download] Note the single-quotes have changed to double-quotes to allow for the interpolation. From one of your previous posts, it looks like you haven't learned about variable interpolation (excuse my presumptuousness if I'm mistaken :). Interpolation allows you to just type your variable names into double-quoted strings, and have Perl automatically replace the value with the variable's value. You can get a detailed (if not gentle) explanation of this feature in perlop. MeowChow s aamecha.s a..a\u$&owag.print	[reply] [d/l]
Re: DBI and Constant by bbfu (Curate) on Feb 12, 2001 at 14:43 UTC
Hrm. I think you'll have to use string concatenation: `use constant DBNAME => "database_test"; ... my $dbh = DBI->connect('DBI:mysql:database=' . DBNAME, 'username', 'pa +ssword') or die "$0: can't connect to DB: " . DBI->errstr . "\n";` [download] The optimizer is probably smart enough to do the concatenation at compile time since it's smart enough to do the function inlining... bbfu Seasons don't fear The Reaper. Nor do the wind, the sun, and the rain. We can be like they are.	[reply] [d/l]
Re: DBI and Constant by TheoPetersen (Priest) on Feb 12, 2001 at 19:49 UTC
If you really want to do this as a constant, you can use the usual interpolation trick for non-scalars: `my $dbh = DBI->connect("DBI:mysql:database=@{[DBNAME]}",'username','pa +ssword') or die();` [download] But I agree that a global is just as obvious to both the reader and the compiler.	[reply] [d/l]
Re: DBI and Constant by lachoy (Parson) on Feb 12, 2001 at 23:17 UTC
For most databases, you can also do: `my $dbh = DBI->connect( 'DBI:mysql:mysql', 'username', 'password' ) \|\| die $DBI::errstr; $dbh->do( 'use ' . DBNAME );` [download] Another option is putting the entire DBI DSN in the constant: `use constant DSN => 'DBI:mysql:database=devel'; ... my $dbh = DBI->connect( DSN, 'username', 'password' ) \|\| die $DBI::errstr;` [download] Chris M-x auto-bs-mode	[reply] [d/l] [select]


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